scholarly journals Alterations in hepatic enzyme activity and progesterone clearance in lactating dairy cows

2010 ◽  
Author(s):  
Caleb Owens Lemley
Keyword(s):  
Enzyme Activity ◽  
Dairy Cows ◽  
Hepatic Enzyme ◽  
Lactating Dairy Cows ◽  
Hepatic Enzyme Activity

scholarly journals Diet-induced alterations in hepatic progesterone (P4) catabolic enzyme activity and P4 clearance rate in lactating dairy cows

2010 ◽  
Vol 205 (3) ◽  
pp. 233-241 ◽  
Author(s):  
C O Lemley ◽  
K A Vonnahme ◽  
L R Tager ◽  
K M Krause ◽  
M E Wilson
Keyword(s):  
Enzyme Activity ◽  
Cytochrome P450 ◽  
Dairy Cows ◽  
Clearance Rate ◽  
Second Phase ◽  
Hepatic Enzyme ◽  
High Fiber ◽  
Hepatic Enzyme Activity ◽  
Fiber Diet ◽  
High Fiber Diet

Elevated rates of steroid clearance may lead to lower reproductive success in several mammalian species. Cytochrome P450 (EC 1.14.14.1) and aldo-keto reductases (AKR; EC 1.1.1.145–151) are involved in the first phase of steroid inactivation, before second phase conjugation and excretion of the steroid metabolite. The current objectives were to determine liver blood flow (LBF), hepatic enzyme activity, and metabolic clearance rate (MCR) of progesterone (P4) in dairy cows consuming isoenergetic and isonitrogenous diets formulated to cause divergent insulin secretion. Insulin concentrations increased by 22% in cows fed the high cornstarch diet, and both cytochrome P450 2C and cytochrome P450 3A activities were decreased (P<0.05) by ∼50%, while AKR1C tended (P<0.10) to be lower in cows fed the high cornstarch diet. LBF was similar between the two diets (1891±91 l/h). MCR of P4 tended (P<0.10) to be lower in cows fed the high cornstarch diet (25±5 l/h×BW0.75) versus the high fiber diet (40±6 l/h×BW0.75). The half-life of P4 was increased (P<0.05) in cows fed the high cornstarch diet (73±10 min) versus the high fiber diet (24±10 min). In summary, cows with elevated insulin concentrations and lower enzyme activity showed a decrease in P4 clearance without any changes in LBF. This dietary relationship with hepatic enzyme activity may explain some of the observed alterations in steroid profiles during the estrous cycle or gestation of the high producing dairy cow.

Hepatic enzyme activity is the major factor determining elimination rate of high-clearance drugs in cirrhosis

Hepatology ◽  
1993 ◽  
Vol 18 (1) ◽  
pp. 54-60 ◽  
Author(s):  
Richard Callaghan ◽  
Paul V. Desmond ◽  
Phillip Paull ◽  
Maurice L. Mashfor
Keyword(s):  
Enzyme Activity ◽  
Elimination Rate ◽  
Hepatic Enzyme ◽  
Hepatic Enzyme Activity ◽  
High Clearance

Diet-Age Pattern for Hepatic Enzyme Activity

1957 ◽  
Vol 61 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Morris H. Ross ◽  
William G. Batt
Keyword(s):  
Enzyme Activity ◽  
Hepatic Enzyme ◽  
Hepatic Enzyme Activity
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